A systematic approach for analyzing the fixturability of parts for machining

Design for manufacturability (DFM) is a growing concern in the academia as well as the industry. However, an evaluation of the manufacturability of the features on a part is incomplete without considering the work-holding requirements of and the pre-processes that have been performed on the part (i.e., the initial state of the part before machining could be a casting or a prismatic block). A feature on a part, which has been evaluated to be manufacturable in its own right, might nor be achievable when it is being machined together with other features in a set-up, if the part cannot be properly fixtured during the machining of this set-up. In this paper, the authors proposed a fuzzy set based fixturability evaluation procedure for establishing fixturing relations between the features on a part and assessing the suitability of these features for use as fixturing features during the machining of other features on the part. The overall fixturability of a part as a whole is evaluated after a set-up plan has been formulated for producing it and a fixture configuration and a fixturability index have been found for each of the set-ups in this set-up plan. Although the methodology has been formulated for machining features of prismatic parts, the approach is also applicable to castings and non-prismatic parts. The fuzzy membership functions for assessing the fixturing properties of features are generic to features that are found on castings and prismatic parts.